Obvious Signs:
* Engine cranks but won't start: This is a classic symptom. If the engine cranks over but refuses to ignite, the fuel pump might be the culprit. No fuel, no start.
* Engine sputtering or hesitation: Intermittent sputtering, especially under acceleration, suggests inconsistent fuel delivery, a common sign of a failing pump.
* Reduced power: The engine may feel sluggish or lack its usual power. This happens because the pump isn't delivering enough fuel.
* Loud humming or whining noise from the fuel tank: Listen carefully when the ignition is turned on. A loud humming or whining sound coming from the fuel tank area (often near the rear passenger side) is a strong indication of a failing fuel pump. This sound is usually most noticeable right after turning the key on. If it only sounds for a few seconds it is possible that it is working and this is normal. If it's constant or louder than normal then you have something to be concerned about.
Less Obvious Signs (Requiring More Investigation):
* Poor fuel economy: A significantly reduced fuel efficiency, even without other symptoms, might hint at an inefficient fuel pump.
* Check engine light illuminated: While the check engine light doesn't specifically indicate a bad fuel pump, it might illuminate due to fuel delivery problems detected by the car's computer. You'll need a code reader to diagnose the specific trouble code.
* Surging or erratic idle: Inconsistent idle speed could also be a sign of inconsistent fuel delivery.
Troubleshooting Steps (Proceed with caution):
* Listen for the fuel pump prime: Turn the ignition key to the "on" position (without starting the engine). You should hear a brief whirring sound from the fuel tank area for a few seconds. This is the pump priming. If you don't hear it, the pump may be faulty or the fuel pump relay is bad.
* Check fuel pressure: This requires a fuel pressure gauge and some mechanical knowledge. Low fuel pressure confirms a problem with the fuel pump or the fuel delivery system. This is best left to a mechanic unless you have experience working on fuel systems.
* Check the fuel pump relay: This is an inexpensive and easy check, but a bad relay can mimic fuel pump failure. The relay can usually be found in the fuse box, and can be replaced relatively easily.
Important Note: Working on the fuel system involves dealing with highly flammable substances. If you're not comfortable working with fuel and auto mechanics, it's best to take your S-10 Blazer to a qualified mechanic for diagnosis and repair. Improperly handling fuel can be dangerous.
